Total synthesis of hydroxy-α- and hydroxy-β-sanshool using Suzuki-Miyaura coupling

Stabilization of Hydroxy-α-Sanshool by Antioxidants Present in the Genus Zanthoxylum

Japanese pepper (sansho, Zanthoxylum piperitum) contains several types of sanshools belonging to N-alkylamides. Because of the long-chain unsaturated fatty acids present in their structure, sanshools are prone to oxidative deterioration, which poses problems in processing. In this paper, we evaluated the effects of antioxidants from the genus Zanthoxylum in preventing sanshool degradation using accelerated tests. An ethanolic extract of segment membranes of the sansho fruit pericarp was incubated at 70 °C for 7 days with different antioxidants to determine the residual amount of hydroxy-α-sanshool (HαS) in the extract. α-Tocopherol (α-Toc) showed excellent HαS-stabilizing activity at low concentrations. Among phenolic acids, we noted that the HαS-stabilizing activity increased with the number of hydroxy groups per molecule. For example, gallic acid and its derivatives exhibited excellent sanshool-stabilizing activity. Quercetin was found to be a superior HαS stabilizer compared with hesperetin and naringenin. However, the effective concentration was much higher for phenolic compounds than for α-Toc. These substances are believed to play a role in preventing the decomposition of sanshools in the pericarp of sansho. These sanshool stabilizers should be useful in the development of new beverages, foods, cosmetics, and pharmaceuticals that take advantage of the taste and flavor of sansho.

A Mini Review on Natural Safeners: Chemistry, Uses, Modes of Action, and Limitations

Herbicide injury is a common problem during the application of herbicides in practice. However, applying herbicide safeners can avoid herbicide damage. Safeners selectively protect crops against herbicide injury without affecting the biological activity of herbicides against the target weeds. However, after long-term application, commercial safeners were found to pose risks to the agricultural ecological environment. Natural safeners are endogenous compounds from animals, plants, and microbes, with unique structures and are relatively environment-friendly, and thus can address the potential risks of commercial safeners. This paper summarizes the current progress of the discovery methods, structures, uses, and modes of action of natural safeners. This study also concludes the limitations of natural safeners and prospects the future research directions, offering guidance for the practical application of natural safeners to prevent herbicide injury. This study will also guide the research and development of corresponding products.

Synthesis of hydroxy-α-sanshool

Hydroxy-α-sanshool was synthesized in a 13% overall yield through eight steps, which included two Wittig reactions that were used to form the carbon skeleton with ethyl 2-oxoacetate and 2 E,4 E-hexadienal being reacted with the appropriate ylides. Impurities in the processes could easily be separated. Ethyl 6-hydroxy-2Z-hexenoate was converted to its E-isomer with catalysis by I2 and 2E,6Z,8E,10E-dodecatetraenoic acid was crystallized from a solution in 1% ethyl acetate in n-hexane.

New Lead Discovery of Herbicide Safener for Metolachlor Based on a Scaffold-Hopping Strategy

The use of herbicide safeners can significantly alleviate herbicide injury to protect crop plants and expand the application scope of the existing herbicides in the field. Sanshools, which are well known as spices, are N-alkyl substituted compounds extracted from the Zanthoxylum species and have several essential physiological and pharmacological functions. Sanshools display excellent safener activity for the herbicide metolachlor in rice seedlings. However, the high cost of sanshools extraction and difficulties in the synthesis of their complicated chemical structures limit their utilization in agricultural fields. Thus, the present study designed and synthesized various N-alkyl amide derivatives via the scaffold-hopping strategy to solve the challenge of complicated structures and find novel potential safeners for the herbicide metolachlor. In total, 33 N-alkyl amide derivatives (2a–k, 3a–k, and 4a–k) were synthesized using amines and saturated and unsaturated fatty acids as starting materials through acylation and condensation. The identity of all the target compounds was well confirmed by ¹H-NMR, ¹³C-NMR, and high-resolution mass spectrometry (HRMS). The primary evaluation of safener activities for the compounds by the agar method indicated that most of the target compounds could protect rice seedlings from injury caused by metolachlor. Notably, compounds 2k and 4k displayed excellent herbicide safener activities on plant height and demonstrated relatively similar activities to the commercialized compound dichlormid. Moreover, we showed that compounds 2k and 4k had higher glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO) activities in rice seedlings, compared to the metolachlor treatment. In particular, 2k and 4k are safer for aquatic organisms than dichlormid. Results from the current work exhibit that compounds 2k and 4k have excellent crop safener activities toward rice and can, thus, be promising candidates for further structural optimization in rice protection.

An Improved and Practical Method for Synthesizing of α-Sanshools and Spilanthol

An efficient and practical route for the synthesis of α-sanshools and spilanthol is described herein. Several modifications of an existing method enabled the preparation of the (2E,6Z,8E,10E)-tetraene precursor of hydroxy-α-sanshool in good yield. A highly selective Wittig reaction employing newly synthesized phosphonium salt with low deliquescence and long-term stability yielded the desired Z-form tetraene. This improved methodology was shown to be applicable to the efficient synthesis of α-sanshool and spilanthol.

Hydroxy-α-sanshool isolated from Zanthoxylum bungeanum attenuates learning and memory impairments in scopolamine-treated mice

Learning and memory impairments are common symptoms of dementia in neurodegenerative disorders.

Peridinin Is an Exceptionally Potent and Membrane-Embedded Inhibitor of Bilayer Lipid Peroxidation

Antilipoperoxidant protein dysfunction is associated with many human diseases, suggesting that bilayer lipid peroxidation may contribute broadly to pathogenesis. Small molecule inhibitors of this membrane-localized chemistry could in theory enable better understanding and/or treatment of such diseases, but currently available compounds have important limitations. Many biological questions thus remain unanswered, and clinical trials have largely been disappointing. Enabled by efficient, building block-based syntheses of three atypical carotenoid natural products produced by microorganisms that thrive in environments of extreme oxidative stress, we found that peridinin is a potent inhibitor of nonenzymatic bilayer lipid peroxidation in liposomes and in primary human endothelial cells. We also found that peridinin blocks monocyte-endothelial cell adhesion, a key step in atherogenesis. A series of frontier solid-state NMR experiments with a site-specifically 13C-labeled isotopolog synthesized using the same MIDA boronate building block-based total synthesis approach revealed that peridinin is completely embedded within and physically spans the hydrophobic core of POPC membranes, maximizing its effective molarity at the site of the targeted lipid peroxidation reactions. Alternatively, the widely used carotenoid astaxanthin is significantly less potent and was found to primarily localize extramembranously. Peridinin thus represents a promising and biophysically well-characterized starting point for the development of small molecule antilipoperoxidants that serve as more effective biological probes and/or therapeutics.

The Molecular Industrial Revolution: Automated Synthesis of Small Molecules

Today we are poised for a transition from the highly customized crafting of specific molecular targets by hand to the increasingly general and automated assembly of different types of molecules with the push of a button. Creating machines that are capable of making many different types of small molecules on demand, akin to that which has been achieved on the macroscale with 3D printers, is challenging. Yet important progress is being made toward this objective with two complementary approaches: 1) Automation of customized synthesis routes to different targets by machines that enable the use of many reactions and starting materials, and 2) automation of generalized platforms that make many different targets using common coupling chemistry and building blocks. Continued progress in these directions has the potential to shift the bottleneck in molecular innovation from synthesis to imagination, and thereby help drive a new industrial revolution on the molecular scale.

Toward Generalization of Iterative Small Molecule Synthesis

Small molecules have extensive untapped potential to benefit society, but access to this potential is too often restricted by limitations inherent to the customized approach currently used to synthesize this class of chemical matter. In contrast, the "building block approach", i.e., generalized iterative assembly of interchangeable parts, has now proven to be a highly efficient and flexible way to construct things ranging all the way from skyscrapers to macromolecules to artificial intelligence algorithms. The structural redundancy found in many small molecules suggests that they possess a similar capacity for generalized building block-based construction. It is also encouraging that many customized iterative synthesis methods have been developed that improve access to specific classes of small molecules. There has also been substantial recent progress toward the iterative assembly of many different types of small molecules, including complex natural products, pharmaceuticals, biological probes, and materials, using common building blocks and coupling chemistry. Collectively, these advances suggest that a generalized building block approach for small molecule synthesis may be within reach.

Polyunsaturated fatty acid amides from the Zanthoxylum genus – from culinary curiosities to probes for chemical biology

A critical and comprehensive review of the discovery, synthesis, and biological activities of alkamides isolated from Zanthoxylum plants and synthetic derivatives thereof.

Intramolecular Diels-Alder Reactions of Tethered Enoate Substituted Furans Induced by Dialkylaluminum Chloride

Gold(I)-catalyzed cycloisomerization of enynols 11 and 17, obtained by Sonogashira coupling, led to the tethered enoate-substituted furans 14 and 19. While attempts at thermal and several Lewis acid induced intramolecular Diels-Alder reactions remained fruitless, dialkylaluminum chloride led to the formation of hexahydroindene and octahydronaphthalene derivatives 20-23. Their formation can be explained by Lewis acid induced opening of the epoxy bridge with transfer of one alkyl group to the intermediate cycloadduct.